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petMD Blogs

The Daily Vet is a blog featuring veterinarians from all walks of life. Every week they will tackle entertaining, interesting, and sometimes difficult topics in the world of animal medicine – all in the hopes that their unique insights and personal experiences will help you to understand your pets.

I live in Miami and only rarely venture into colder climes with my pets in tow. Consequently, I have little first-hand knowledge of cold weather issues. Yet I’m constantly asked about them with respect to travel. As in, how cold is too cold? How long can my dog or cat withstand low temps in cargo? At what point is it inhumane to allow a pet to fly?

This issue came up for me (again) a couple of days ago while reading the acclimation statement on the health certificate attached to the kitten described in my Christmas Eve post.

So you know, airlines typically require a certificate or statement of “acclimation” whenever an animal is flown. Airlines require this so that animals may be shipped in accordance with veterinary recommendations, effectively restricting their liability with respect to temperature in the event of animal illness or death.

In this shipped kitten’s case, the certificate read as follows: “...35 to 85 degrees.” It did not specify Celsius or Fahrenheit. (It might’ve been in Kelvin or Rankine for all we know.) Neither did it specify a time frame. I mean, how long is too long?

For heat, we know that once you reach certain easily-achieved high temperatures (as in a hot car), animals cannot live beyond a few minutes. This is universally true for all. Yet when it comes to the lower end of the scale, a lot depends on the animals’ weight, conformation and length of the exposure.

Sitting on the tarmac for three hours? No 1.5-pound kitten should suffer 35 degree temps (Fahrenheit) for this length of time. He’ll almost always survive, but the experience gets filed under cruelty, nonetheless. Common sense dictates that much.

But apart from experiencing it first-hand and agreeing roundly that a bad time would be had by all in similar circumstances, how would we really know? Who’s to say whether one cat’s near-freezing is another dog’s ideal temperature? And how does the time of exposure factor into it (yet another level of vagary we’d be remiss to neglect)?

Thankfully, modern veterinary medicine has gone out of its way to establish guidelines for this. Not only does the USDA issue basic standards (under USDA Transportation Standards 9CFR 3.18 which state that “ambient temperatures in airport holding facility must not dip below 45 degrees or above 85 degrees for over 4 hours [for dogs]”) but Tufts University’s vet school has also made inroads into this issue (at least for dogs).

Tufts says, “Read score off diagonal bars, by dog size: To determine score, draw a line up from the current temperature and parallel to the dotted lines, and read score on bars [for which 5 is an ideal dog and 1 is an emaciated, poor-conditioned dog]." Additional tweaks to the scale are offered in the accompanying verbiage, being sure to add, “Common sense must be used to take into account the duration of exposure to any given temperature when assessing risk; even brief periods of high heat can be very dangerous, whereas a similar duration of exposure to cold temperatures would not be life-threatening.”

But "common sense" is not always so common, right? Yes, even Tufts shirks the length of exposure issue. But luckily, the USDA's 4-hour standard can be reasonably applied to help define the specs.

This may all sound pretty basic to you. Yes, it should be obviously commonsensical that dogs and cats shouldn’t have to suffer certain degrees of frigid temps. Nevertheless, this is crucial stuff for veterinarians like me who have to rely on evidence-based standards––not experience-influenced determinations––to make recommendations for animal welfare in legal and regulatory settings.

It happens more often than you might think. As in this actual legal case: Is a low body-fat sighthound OK tethered out in 20 to 30 degree weather for 3 hours a day? Or when it comes to cases like my kitten's: Is it OK to issue blanket statements about the temp a 1.5-pound 8-weeker can theoretically experience without specifying a timeframe?